SAMPLING DESIGN:
Daily maximum and minimum temperatures from up to eight locations at
HBEF were measured from October, 1955 through February, 2013 using
mechanical hygrothermographs in weather shelters at seven locations.
Six locations are in rain gage openings: 1/1A, 6, 14, 17, 23, and 24.
One location is adjacent to the Headquarters building. At each
station, air temperature (and usually relative humidity) was recorded
by Belfort hygrothermographs housed in standard Stevenson screens, 5
feet off the ground. Standard, maximum and minimum thermometers were
housed in the shelters alongside the hygrothermographs for weekly
calibration checks of the current, max and min temperatures captured
on the chart. The hygrothermograph charts were changed weekly, at
which time the thermometers were read. Daily maximum and minimum
temperatures were read manually from the charts. Correction for
disagreement with the standard thermometers were seldom made as
agreement is usually within 2 degrees F. The hygrothermographs were
readjusted annually and rotated from site to site after lab
calibration to prevent instrument bias. Maximum and minimum
temperatures were converted from Fahrenheit to Celsius. Average daily
temperature is calculated from the maximum and minimum.
Beginning during 2011, Campbell Scientific HMP50/60 or CS215
thermistors in six-plate Gill shields recorded daily maximum and
minimum temperatures at each location. Gill shields were replaced with
Apogee aspirated shields by mid-2016. Digital sensors and
hygrothermographs were operated in the same clearing for an overlap
period of at least one full year at all stations, and adjustments for
changes in sensor and radiation shield technology were made by using
linear interpolation to smooth median monthly differences to a daily
scale. Prior to the transition to digital sensors, if a weather
station was not operating, the value for that day was estimated from
values at the other stations and was not not flagged. Currently,
missing values are estimated according to linear regression with the
best matched location and are indicated with a flag. Prior to the
transition, the Fahrenheit to Celsius conversion and rounding to whole
degrees Centigrade leads to considerable underrepresentation of -5, 0,
5, 10, etc. values. After the transition, values are rounded to the
nearest 0.5 degree Centigrade. Station 24 is not included in this
revision of the data because the transition to digital has not been
completed.
VARIABLES:
date: format = yyyy-mm-dd
STA: values are "HQ", "STA1", "STA14",
"STA17", "STA23", "STA6"
MAX: Maximum daily temperature (numeric; Celsius)
MIN: Minimum daily temperature (numeric; Celsius)
AVE: Average daily temperature (numeric; Celsius)
Flag: 0 = directly measured; 1 = estimated from nearby station; NA =
not recorded (prior to the transition to digital).